What about Aloysia virgata? It's called Sweet Almond Bush, but it will grow into a small tree.

Kevin : )

and of course citrus. There is an orange that is grown just for the flower and fragrance. There is also a lemon that blooms up to 4 times a year giving you a long season.

I second the citrus... especially lemons. The fragrance of the flowers is fantastic and they're easy to grow here.

Sweet acacia, the AZ native, makes a small tree and smells wonderful.

Acacia berlandieri
Eysenhardtia orthocarpa
Havardia pallens
Sophora secundiflora

just to name a few..